Supplying multiple procs to initialization

Ruby
1

One of my libraries previously required code like this:

Convert markup to HTML, doing something

useless with links and commands

owl = OWLScribble.new( markup )
owl.wiki_links.each{ |link|
# do something useful to the link
}
owl.wiki_commands.each{ |command|
# do something useful with the command
}
html = owl.to_html

I have changed it so that the user can instead describe how to handle
links and commands in general, so that during initialization the
library doesn’t waste time or code lines doing something useless:

owl = OWLScribble.new( markup ) do |owl|
owl.handle_wiki_link do |tag, page, link_text|
# do something useful to the link
end
owl.handle_wiki_command do |tag, command, params|
# do something useful to the command
end
end
puts owl.to_html

The syntax you see above is my current favorite choice for specifying
these two procs. Alternatives that I have rejected as less elegant:

Deferred initialization

owl = OWLScribble.new( markup )
owl.handle_wiki_link{ … }
owl.handle_wiki_command{ … }
owl.run
puts owl.to_html

proc params

do_link = proc{ … }
do_command = proc{ … }
owl = OWLScribble.new(
markup,
:handle_wiki_link=>do_link,
:handle_wiki_command=>do_command
)
puts owl.to_html

Can anyone suggest a more elegant way of supplying multiple processing
procs that should be used during initialization, on a per-instance
basis?

2

On 25.11.2007 19:36, Phrogz wrote:

}
owl.handle_wiki_command do |tag, command, params|
owl.handle_wiki_link{ … }
:handle_wiki_command=>do_command
)
puts owl.to_html

Can anyone suggest a more elegant way of supplying multiple processing
procs that should be used during initialization, on a per-instance
basis?

Why not just

owl = OWLScribble.new(
markup,
:handle_wiki_link => lambda {…},
:handle_wiki_command => lambda {…}
)

Kind regards

robert

3

On Nov 25, 12:42 pm, Robert K. [email protected] wrote:

# do something useful to the link

owl = OWLScribble.new( markup ) do |owl|
these two procs. Alternatives that I have rejected as less elegant:
do_command = proc{ … }

Why not just

owl = OWLScribble.new(
markup,
:handle_wiki_link => lambda {…},
:handle_wiki_command => lambda {…}
)

I personally lump that in with the other option that happens to create
the procs outside the function call. As you show it, with a single
ellipsis for each proc’s content, it feels clean. I expect
handle_wiki_link to be on the order of 20 lines, and
handle_wiki_command to take 50-100 lines. That seems excessive to
inline into a method call.

4

2007/11/25, Phrogz [email protected]:

owl.wiki_links.each{ |link|

The syntax you see above is my current favorite choice for specifying
do_link = proc{ … }
basis?
the procs outside the function call. As you show it, with a single
ellipsis for each proc’s content, it feels clean. I expect
handle_wiki_link to be on the order of 20 lines, and
handle_wiki_command to take 50-100 lines. That seems excessive to
inline into a method call.

Good point. I did not know that they would become that complex. In
that case it’s a reasonable option to define them elsewhere. But in
that case I’d probably even define them as constants - unless you need
the local binding.

Kind regards

robert